Venous Excess Ultrasound for Fluid Assessment in Complex Cardiac Patients With Acute Kidney Injury

Introduction: The introduction of point-of-care ultrasound (POCUS) into clinical practice has revolutionized bedside hemodynamic assessment in recent years. POCUS has expanded its utility to include evaluating and grading venous congestion through Doppler analysis of venous blood flow. This innovative technique, VExUS (venous excess ultrasound), comprehensively evaluates venous congestion across multiple sites, including the inferior vena cava (IVC), hepatic vein, portal vein, and intrarenal vasculature. The aim of the current study was to determine whether venous excess ultrasound can help guide fluid therapy in complex patients with acute kidney injury (AKI) in addition to the standard physical examination and imaging. Methods: Our current study shows instructive 18 clinical adult cases (enrolled between January 2024 and May 2024) to determine whether venous excess ultrasound can help guide fluid therapy in complex cardiac patients with acute kidney injury, in addition to the standard physical examination and imaging. Results: VExUS was pivotal in guiding fluid therapy in all complex patients with AKI and suspected right ventricular dysfunction. By integrating VExUS findings with clinical data and cardiac ultrasound results, clinicians were able to make patient-favouring decisions regarding fluid management, diuresis, and vasopressor therapy, addressing critical aspects of conditions such as septic shock, heart failure, and acute kidney injury. Conclusions: In our study of VExUS in sick patients with AKI, we concluded that VExUS proved to be a valuable tool for fluid assessment and management. By providing real-time visualization of venous congestion, VExUS allowed for more precise and individualized fluid management strategies. This led to improved decision-making regarding fluid administration and removal, helping to prevent both fluid overload and hypovolemia. Consequently, the use of VExUS contributed to better clinical outcomes in patients with AKI, demonstrating its potential as a critical component in the management of fluid balance in this vulnerable patient population.


Introduction
In critically ill patients, monitoring hemodynamic parameters is crucial for optimizing perfusion and preventing organ dysfunction [1,2].Traditionally, the focus has been on maintaining adequate cardiac output and arterial blood pressure.However, the significance of venous congestion, often overlooked, plays a significant role in organ perfusion [3,4].Traditional hemodynamic methods like central venous pressure (CVP) may not capture the complexity of venous congestion, emphasizing the need for advanced techniques like point-of-care ultrasound (POCUS) and innovative tools like venous excess ultrasound (VExUS) grading.Regular monitoring and tailored interventions based on VExUS grading can significantly avoid indiscriminate fluid loading and preserve optimal perfusion dynamics, enhancing patient outcomes and reducing mortality risks.
In recent years, the paradigm of assessing venous congestion has significantly transformed with the advent of VExUS.This innovative bedside, four-part ultrasound-based approach, pioneered by Beaubien-Souligny et al., presented a revolutionary method for evaluating venous blood flow through key vasculatures, including the inferior vena cava (IVC), hepatic vein, portal vein, and intrarenal vasculature [5].The culmination of these measurements results in a VExUS grade, a novel indicator for venous congestion.This approach originated from a meticulous post-hoc analysis correlating ultrasound grading parameters with the risk of acute kidney injury (AKI) development in cardiac surgery patients [5][6][7].The VExUS score is a clinical tool with a four-part ultrasound approach to assess venous congestion by evaluating IVC diameter, hepatic vein Doppler, portal vein Doppler, and intrarenal vein Doppler.Venous Doppler imaging assesses the return flow pattern of venous congestion once it is identified.Venous congestion can be evaluated at the liver, the portal, and the intra-renal vein.Venous flow in the hepatic vein provides information on the mechanics of the right heart-filling patterns.Flow patterns on the portal and intra-renal veins offer information on the degree of pressure transfer to the peripheral organs [5,6].
POCUS combined with the VExUS score offers invaluable advantages in assessing and managing venous congestion across various medical conditions.One of its primary benefits lies in early detection, enabling clinicians to identify venous congestion promptly in patients with heart failure, liver disease with kidney disease, and fluid overload.This early detection is pivotal as it facilitates timely interventions, potentially averting complications.Moreover, POCUS with VExUS is non-invasive, ensuring patient safety by avoiding exposure to ionizing radiation or contrast agents.This makes it a suitable option for repeated assessments of critically ill patients.VExUS provides real-time images, allowing clinicians to monitor changes in venous congestion over time.This is especially important in dynamic clinical situations where a patient's condition may change rapidly.VExUS is conducted at the patient's bedside and provides immediate insights, aiding clinicians in making swift and informed decisions, a vital aspect in critical care settings [5][6][7].Additionally, the VExUS score assists in stratifying patients based on congestion severity, enabling tailored treatments and interventions.VExUS may play a crucial role in preventing unnecessary interventions by distinguishing between venous congestion and other conditions with similar symptoms.Once venous congestion is identified, effective treatment strategies, such as diuretic therapy or fluid management adjustments, can be employed.The VExUS protocol's focus on assessing the venous-to-arterial blood flow ratio in the renal and hepatic veins differentiates it.Additionally, there are reports of IVC diameters and collapsibility indexes with significant correlations with CVP [5][6][7][8].The combination of VExus with IVC diameters and collapsibility indices with CVP correlations allows clinicians to diagnose the underlying cause of congestion, whether cardiogenic factors like heart failure or non-cardiogenic issues like renal dysfunction.In short, POCUS with the VExUS score is an indispensable tool that enhances the precision of diagnosis, guides treatment, and ultimately improves patient outcomes in the complex realm of venous congestion management [5][6][7][8][9].

Aim
The study aims to determine whether venous excess ultrasound can help guide fluid therapy in complex patients with acute kidney injury, in addition to the standard physical examination and imaging, and whether it can be of educational value for further prospective studies.

Study type and duration
A case-series study was conducted in a tertiary hospital from January 2024 to May 2024.

Inclusion and exclusion criteria
Individuals diagnosed with AKI as per the KDIGO classification and complex clinical conditions, such as suspected right ventricular pathology and dilated IVC with challenging fluid management scenarios as per the treating physician, were enrolled in the study.Participants aged 18 years and older were included, provided they gave informed consent.
Exclusion criteria encompassed non-consenting patients, individuals below 18 years, and those with known allergies to ultrasound gel or related substances.Additionally, patients in critical condition, those with inadequate imaging windows, pregnant or breastfeeding women, individuals with chronic atrial fibrillation, mechanical cardiac assistance, uncontrolled low blood pressure, or undergoing specific medical interventions like veno-venous hemofiltration or dialysis were excluded from the study.These criteria were established to ensure the study's scientific integrity, ethical compliance, and participant safety.

Data collection
The baseline patient information recorded includes patient demographics, existing co-morbidities, and the reason for admission.Clinical assessments, including hemodynamic factors, fluid balance, and ventilator parameters, including the type of ventilation (invasive or non-invasive), FiO 2 (fraction of inspired oxygen), tidal volume, respiratory rate, and end-expiratory pressure, were analyzed.Biological parameters vital for monitoring the patient's physiological state encompassed haemoglobin levels, hematocrit levels, sodium levels, arterial lactate levels, and daily serum creatinine levels.Approval from the Institutional Review Board was obtained for the current study.

Ultrasound measurements
The assessment of the VExUS score and meticulous ultrasound measurements were conducted in adherence to established protocols.VExUS grading and Doppler patterns are shown in Figure 1.Recent studies on the VExUS application are summarized in Table 1.2024

TABLE 1: A table depicting recent studies on VExUS application
The VExUS score for AKI patients was defined as congestive (VExUS ≥ 2): patients with a VExUS score of 2 or higher, indicating moderate to severe renal congestion; or non-congestive (VExUS < 2): patients with a VExUS score below 2, indicating no congestion.
Ultrasound examinations were performed in conjunction with simultaneous ECG monitoring to precisely identify the phases of the cardiac cycle.The IVC diameter was precisely measured at 1.0 cm from its junction with the right atrium in the subcostal view, with both maximum and minimum diameters recorded.The percentage change in diameter was calculated, offering valuable data for assessment.Additionally, pulsedwave (PW) Doppler assessment in the liver hilum measured the maximum velocity (V max ) and minimum velocity (V min ) of the portal vein [10].These values were crucial for computing the Portal Pulsatility Index (PI) using the formula PI = (V max − V min )/V max , providing essential insights into hemodynamic status.PW Doppler measurements were also conducted in the interlobar veins of each kidney's upper, median, and lower segments [11].The resulting intrarenal venous flow patterns were meticulously classified according to established waveform patterns, enhancing the depth of the analysis [11,12].The ultrasound findings guided fluid therapy, diuretic administration, and other interventions to optimize the patient's fluid balance.

Definition and outcomes
The VExUS score was determined at four crucial junctures: within 24 hours of admission, after the first day (between 24 and 48 hours), following the second day (between 48 and 72 hours), and at the point of discharge [13].Patients were categorized into congestive (VExUS ≥ 2) or non-congestive (VExUS < 2) groups, with grade 2 indicating moderate congestion and grade 3 marking severe congestion.
AKI stages were defined as follows: Stage 1 was defined as an increase in serum creatinine (SCr) by ≥ 0.3 mg/dL or to ≥ 1.5 times baseline or reduced urine output (< 0.5 mL/kg/h) for 6-12 hours.Stage 2 was defined as a serum creatinine increase to ≥ 2.0-2.9 times baseline or reduced urine output for ≥ 12 hours.Stage 3 was defined as serum creatinine up to 3.0 times baseline, serum creatinine increased to ≥4.0 mg/dL, initiation of kidney replacement therapy, minimal urine output for ≥ 24 hours, or anuria for ≥12 hours.
Baseline serum creatinine, representing kidney function before admission, was determined within three months before hospitalization.If the baseline serum creatinine was unavailable and there was no history of renal disease, we estimated it to be 1 mg/dL.Furthermore, the study examined the 28-day mortality rate, recording the number of patients who passed away within 28 days of their admission.

Results
A total of 18 patients (n = 3 representative cases shown below and n = 15 cases shown in Tables 2-4) were studied (median age 65; out of 15, 9 were male (60%)).In addition to the standard physical examination and diagnostic imaging, VExUS was performed on all the patients.The clinical cases and the utilization of VExUS played a crucial role in guiding the management and ultimately improving the patient's condition.We present three representative cases where VExUS-guided therapy.

Case series
Instructive Case and Case Series-I Clinical presentation and POCUS results: A 70-year-old male with a history of alcoholic cirrhosis and severe congestive cardiac failure presented with worsening respiratory distress and acute kidney injury.On examination, the patient exhibited tense ascites and anasarca.Hemodynamic parameters indicated signs of fluid overload and compromised cardiac function.Laboratory tests revealed an elevated serum creatinine level of 2.1 mg/dl (0.7-1.1), indicating acute kidney injury.His POCUS examination through VExUS was revealed (Figures 2-5).Discussion: This case study investigates the effectiveness of VExUS assessment in distinguishing between chronic venous congestion and acute left ventricular dysfunction, guiding precise therapeutic interventions for patients with complex cardio-renal syndromes.Integrating such techniques into routine clinical practice is essential for improving diagnostic accuracy, tailoring treatment strategies, and ultimately enhancing patient outcomes and quality of life.Patients managed on similar lines with the help of VeXUS are shown in Table 2.
Instructive Case 2 and Case Series II Clinical presentation and POCUS results: An 84-year-old male with significant pulmonary hypertension and mitral regurgitation was admitted with acute kidney injury and respiratory distress.Upon admission, the patient exhibited systemic congestion, including edoema and bilateral crackles in both lower lung lobes.Initial vital signs showed a blood pressure of 140/90 mm Hg.He received oxygen via nasal prongs and received epinephrine and dobutamine infusions to maintain hemodynamic stability.His serum creatinine level was elevated at 2 mg/dl (0.7-1.1), indicating acute kidney injury.VExUS evaluation revealed inferior vena cava diameter: severely dilated, fixed, and congestion grade: 3 (severe).
Treatment approach: He received oxygen via nasal prongs and received epinephrine and dobutamine infusions to maintain hemodynamic stability.Based on VExUS findings, a furosemide infusion was initiated, leading to progressive improvement in the patient's oxygen requirement, hemodynamic and acute kidney injury over the subsequent week.
Discussion: This case highlights the importance of VExUS evaluation in managing complex cases where coexistent pulmonary hypertension complicates the interpretation of elevated CVP and IVC diameters.Through VExUS, an accurate assessment of venous congestion was possible, which, in turn, guided the initiation of diuretic therapy.This approach successfully managed the patient's congestive heart failure, improving his clinical condition.Patients managed on similar lines with the help of VeXUS are shown in Table 3.

Instructive Case-3 and Case Series
Clinical presentation and POCUS results: A 60-year-old male with a history of pulmonary hypertension was admitted with worsening anasarca, dyspnea, and acute kidney injury (serum creatinine 2.3 mg/dl (0.7-1.1)).Initial intravenous furosemide provided only a partial response.Daily VExUS assessments revealed: IVC diameter: dilated; congestion grade: 3 (severe).
Treatment approach: Based on the VExUS assessment findings, aggressive diuretic therapy was initiated.
The patient responded well to the diuretic treatment, and subsequent VExUS assessments showed improvement in congestion grade and reduced IVC dilation.Consequently, the patient's clinical status improved significantly, leading to a decrease in serum creatinine levels from 2.3 mg/dl to 1 mg/dl (0.7-1.1).
Discussion: Implementing VExUS assessments provided valuable insights into congestion dynamics, allowing precise adjustment of diuretic therapy, preventing diuretic resistance, facilitating efficient decongestion, and improving renal function and overall clinical status.VExUS assessments offer a novel approach for real-time monitoring of congestion levels, enabling tailored diuretic therapy.Patients managed on similar lines with the help of VeXUS are shown in Table 4.

Discussion
VExUS is a valuable tool in managing fluid therapy for complex patients, particularly those with AKI combined with right heart failure, pulmonary hypertension, COPD, or pulmonary edema.VExUS assesses venous congestion using ultrasound to evaluate the IVC and hepatic, portal, and renal veins [1][2][3][4].This score helps in identifying fluid overload, which is critical in patients where fluid balance is challenging.
In patients with AKI and right heart failure or pulmonary hypertension, excessive fluid can worsen heart function and kidney injury.VExUS aids in tailoring fluid therapy by providing real-time data on venous congestion, thus preventing fluid overload.For COPD and pulmonary edoema patients, accurate fluid management is crucial to avoid exacerbating respiratory issues.By using VExUS, clinicians can make informed decisions on fluid administration or restriction, diuretic use, and other interventions.This individualized approach helps optimize fluid status, improve patient outcomes, and reduce the risk of complications related to both under-and over-hydration.Thus, VExUS is an essential non-invasive method for managing fluid therapy in these complex patient populations [1][2][3][4][5][6].
Often, detecting venous congestion linked to potential end-organ dysfunction necessitates invasive monitoring or ultrasound assessments.However, the practical difficulty revolves around judicious fluid administration and removal.An isolated analysis of IVC ultrasound may not give all the information needed.The limitations of the current study were that it was a pilot study from a single center.The treatment of the patients was decided by the treating physician in consultation with the intensivist and nephrologist.Larger studies are needed to establish the cause-and-effect relationship between the risk factors in high-risk patients and to determine if VExUS is a suitable tool to diagnose and follow venous congestion in these complex patients.
To further enhance critical care practices, it is imperative to invest in education and training initiatives for healthcare providers to harness the potential of VExUS effectively.Moreover, future research should explore its applications in larger patient cohorts and assess its long-term impact on mortality and morbidity, ushering in an era of improved, tailored patient care.

Conclusions
VExUS emerged as a valuable tool in assessing splanchnic venous congestion, guiding fluid therapy, and improving patient outcomes.The ability to stratify venous congestion severity allowed for tailored interventions leading to optimized renal perfusion and reduced right ventricular strain.Incorporating VExUS into the diagnostic algorithm for complex AKI cases with suspected right ventricular pathology holds promise for enhancing patient care and outcomes.
was received from any organization for the submitted work.Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work.Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

2 A 3 A 5 A
year-old female with a history of systolic heart failure presented with worsening fatigue and reduced urine inhibitors initiated, guided by VExUS findings, and prevented acute kidney injury.Regular follow-ups showed stabilized renal function.63-year-old female with a history of heart failure and chronic obstructive pulmonary disease presented with fatigue and decreased exercise tolerance Chronic venous congestion (grade 2); dilated IVC Optimized heart failure management and diuretic adjustment led to improved cardiac output and alleviation of symptoms.64-year-old female with a history of diabetes and coronary artery disease was admitted with acute onset dyspnea and hypotension (indicating acute left ventricular dysfunction) inotropic support and diuretics.Significant improvement in cardiac function and resolution of symptoms.4 A 70-year-old male with a history of atrial fibrillation and liver cirrhosis presented with abdominal distension and oliguria Congestion (grade 2); moderately dilated IVC Paracentesis and diuretic therapy done.Reduction in ascites and improved renal perfusion and serum creatinine.75-year-old male with a history of hypertension and endstage renal disease on hemodialysis presented with fluid overload and worsening renal function Severe congestion (grade 3); markedly dilated IVC Aggressive ultra-filtration during hemodialysis sessions and initiation of appropriate cardiac medications.Improved fluid balance and renal function.

A
detailed VExUS may give more practical information to patients with suspected systemic venous congestion.While VExUS may not offer definitive guidance on fluid necessity, it can serve as a guidepost, signalling when to halt fluid resuscitation and pinpointing patients likely to benefit from fluid removal.The traditional emphasis on cardiac output or forward flow in fluid resuscitation overlooks the pivotal role of venous congestion.Extensive literature indicates that beyond a certain point, venous congestion, as characterized by parameters such as CVP or venous Doppler indices, negates the benefits of augmented forward flow[5,10,11,[14][15][16]. Clinicians must recognize the dual nature of fluids, utilizing bedside tools astutely to tailor fluid interventions, thus averting pathological markers of venous congestion[17].This awareness underscores the need for a nuanced approach where clinical understanding and precise tools guide fluid management strategies, ultimately enhancing patient outcomes.The cases presented in this study underscore the significant impact of VExUS in evaluating venous congestion across the vital vasculature, enabling tailored interventions in critical adult patients with acute kidney injury.It helped distinguish between chronic venous congestion and acute cardiac dysfunction, facilitating precise adjustments in diuretic therapy to prevent indiscriminate fluid loading and diuretic resistance.VExUS's real-time monitoring capability aligns seamlessly with the concept of precision medicine, offering personalized, evidence-based interventions based on individual patient characteristics and responses[17][18][19].VExUS aids in making precise fluid management decisions, ensuring that the heart and kidneys are not further compromised by fluid overload.By offering a non-invasive, real-time assessment of venous congestion, VExUS allows clinicians to tailor fluid therapy, use diuretics effectively, and implement other interventions as needed.This individualized approach improves patient outcomes by optimizing fluid status, reducing the risk of complications, and enhancing the overall management of AKI in patients with cirrhosis, COPD, and right heart failure.

TABLE 2 : Below is the table of patients where VExUS assessments helped in guiding the treatment in five patients with acute kidney injury and multisystemic involvement in the form of heart failure/cirrhosis/pulmonary edema Clinical presentation VExUS assessment VExUS-guided treatment
1A 65-year-old male, post-pulmonary embolism, presented with right-sided heart failure symptoms.